1. Field of the Invention
The invention is directed to a leveling suspension system that is provided with a pivoting arrangement which is particularly useful on an agricultural combine.
2. Description of the Prior Art
Vehicles are primarily designed to operate on level ground. Accordingly operation in hilly terrain, in which the support surface is oriented more or less at an incline, may lead to reduction in the performance of the machine. In the case of a combine designed for operation on level ground, a support arrangement is conventionally provided that contains a frame configured as an axle housing whose end is provided with a flange that is used to connect it to a mating flange on a final drive housing. If this configuration is retained, operation on an incline must either accept losses to the grain crop or groups of operating components in the combine must be designed so that they can compensate for the inclined operation.
On the other hand, suspension arrangements have already been proposed by means of which a machine operating on a hillside or on other inclined surfaces can be brought into a horizontal position.
Thus U.S. Pat. No. 3,731,470 discloses a combine with final drives each of which is attached to a pivot arm and supported in bearings in a mount fastened to a frame. The pivot arms are pivoted by means of a hydraulic cylinder about a horizontal axis that is concentric to a leg of the pivot arm configured as a sleeve. The final drive is pivoted with the pivot arm in a vertical plane and consequently adjusts the height or the inclination of the combine in response to signals determined by an inclination sensor. In addition a chain drive is provided in the pivot arm that transmits the power from a gearbox to the final drive.
This pivoting arrangement has the disadvantage that the pivot arm must contain a gear drive that transmits power from the power supply to the final drive and that considerably increases the overall width of the combine.
It is further known from U.S. Pat. No. 3,703,298 and Prospectus: Laverda mietitrebbia autolivellante M 100 AL, Ditta Pietro Laverda 1..sup.a edizione 1971-FOZ to pivot the entire axle body of a combine in a plane transverse to the direction of travel and to transmit power by means of shafts with universal joints.
The cost of equipping a vehicle with a pivoting arrangement of this type is very high.
German Patent-1 066 878 and 808 183 each show the suspension of a wheel of a drive axle of an agricultural tractor, where the wheel can be pivoted in a vertical plane and furthermore can be fixed in a particular position. By virtue of this arrangement the agricultural tractor can be operated on a road with a low center of gravity and in the field with a high center of gravity position, which helps to avoid damage to field crops by the agricultural tractor.
Furthermore it is known practice with agricultural tractors as well as other vehicles, in particular utility vehicles, to connect wheels, not adjustable in height, but directly or through a retainer that is usually configured as final drive.
This type of machine includes every sort of vehicle, such as agricultural machines, construction vehicles, logging vehicles, off-the-road vehicles and the like.